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 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
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 ****************************************************************************/

/*
 *  NIST SP800-38C compliant CCM implementation
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

/*
 * Definition of CCM:
 * http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf
 * RFC 3610 "Counter with CBC-MAC (CCM)"
 *
 * Related:
 * RFC 5116 "An Interface and Algorithms for Authenticated Encryption"
 */

#include "tls/config.h"

#if defined(MBEDTLS_CCM_C)

#include "tls/ccm.h"

#include <string.h>

#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
#if defined(MBEDTLS_PLATFORM_C)
#include "tls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#endif							/* MBEDTLS_PLATFORM_C */
#endif							/* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize(void *v, size_t n)
{
	volatile unsigned char *p = (unsigned char *)v;
	while (n--) {
		*p++ = 0;
	}
}

#define CCM_ENCRYPT 0
#define CCM_DECRYPT 1

/*
 * Initialize context
 */
void mbedtls_ccm_init(mbedtls_ccm_context *ctx)
{
	memset(ctx, 0, sizeof(mbedtls_ccm_context));
}

int mbedtls_ccm_setkey(mbedtls_ccm_context *ctx, mbedtls_cipher_id_t cipher, const unsigned char *key, unsigned int keybits)
{
	int ret;
	const mbedtls_cipher_info_t *cipher_info;

	cipher_info = mbedtls_cipher_info_from_values(cipher, keybits, MBEDTLS_MODE_ECB);
	if (cipher_info == NULL) {
		return (MBEDTLS_ERR_CCM_BAD_INPUT);
	}

	if (cipher_info->block_size != 16) {
		return (MBEDTLS_ERR_CCM_BAD_INPUT);
	}

	mbedtls_cipher_free(&ctx->cipher_ctx);

	if ((ret = mbedtls_cipher_setup(&ctx->cipher_ctx, cipher_info)) != 0) {
		return (ret);
	}

	if ((ret = mbedtls_cipher_setkey(&ctx->cipher_ctx, key, keybits, MBEDTLS_ENCRYPT)) != 0) {
		return (ret);
	}

	return (0);
}

/*
 * Free context
 */
void mbedtls_ccm_free(mbedtls_ccm_context *ctx)
{
	mbedtls_cipher_free(&ctx->cipher_ctx);
	mbedtls_zeroize(ctx, sizeof(mbedtls_ccm_context));
}

/*
 * Macros for common operations.
 * Results in smaller compiled code than static inline functions.
 */

/*
 * Update the CBC-MAC state in y using a block in b
 * (Always using b as the source helps the compiler optimise a bit better.)
 */
#define UPDATE_CBC_MAC                                                      \
	for (i = 0; i < 16; i++)                                               \
		y[i] ^= b[i];                                                       \
																			\
	if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, y, 16, y, &olen)) != 0)	\
		return(ret);

/*
 * Encrypt or decrypt a partial block with CTR
 * Warning: using b for temporary storage! src and dst must not be b!
 * This avoids allocating one more 16 bytes buffer while allowing src == dst.
 */
#define CTR_CRYPT(dst, src, len)                                            \
	if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctr, 16, b, &olen)) != 0)  \
		return(ret);                                                         \
																				\
	for (i = 0; i < len; i++)                                                 \
		dst[i] = src[i] ^ b[i];

/*
 * Authenticated encryption or decryption
 */
static int ccm_auth_crypt(mbedtls_ccm_context *ctx, int mode, size_t length, const unsigned char *iv, size_t iv_len, const unsigned char *add, size_t add_len, const unsigned char *input, unsigned char *output, unsigned char *tag, size_t tag_len)
{
	int ret;
	unsigned char i;
	unsigned char q;
	size_t len_left, olen;
	unsigned char b[16];
	unsigned char y[16];
	unsigned char ctr[16];
	const unsigned char *src;
	unsigned char *dst;

	/*
	 * Check length requirements: SP800-38C A.1
	 * Additional requirement: a < 2^16 - 2^8 to simplify the code.
	 * 'length' checked later (when writing it to the first block)
	 */
	if (tag_len < 4 || tag_len > 16 || tag_len % 2 != 0) {
		return (MBEDTLS_ERR_CCM_BAD_INPUT);
	}

	/* Also implies q is within bounds */
	if (iv_len < 7 || iv_len > 13) {
		return (MBEDTLS_ERR_CCM_BAD_INPUT);
	}

	if (add_len > 0xFF00) {
		return (MBEDTLS_ERR_CCM_BAD_INPUT);
	}

	q = 16 - 1 - (unsigned char)iv_len;

	/*
	 * First block B_0:
	 * 0        .. 0        flags
	 * 1        .. iv_len   nonce (aka iv)
	 * iv_len+1 .. 15       length
	 *
	 * With flags as (bits):
	 * 7        0
	 * 6        add present?
	 * 5 .. 3   (t - 2) / 2
	 * 2 .. 0   q - 1
	 */
	b[0] = 0;
	b[0] |= (add_len > 0) << 6;
	b[0] |= ((tag_len - 2) / 2) << 3;
	b[0] |= q - 1;

	memcpy(b + 1, iv, iv_len);

	for (i = 0, len_left = length; i < q; i++, len_left >>= 8) {
		b[15 - i] = (unsigned char)(len_left & 0xFF);
	}

	if (len_left > 0) {
		return (MBEDTLS_ERR_CCM_BAD_INPUT);
	}

	/* Start CBC-MAC with first block */
	memset(y, 0, 16);
	UPDATE_CBC_MAC;

	/*
	 * If there is additional data, update CBC-MAC with
	 * add_len, add, 0 (padding to a block boundary)
	 */
	if (add_len > 0) {
		size_t use_len;
		len_left = add_len;
		src = add;

		memset(b, 0, 16);
		b[0] = (unsigned char)((add_len >> 8) & 0xFF);
		b[1] = (unsigned char)((add_len) & 0xFF);

		use_len = len_left < 16 - 2 ? len_left : 16 - 2;
		memcpy(b + 2, src, use_len);
		len_left -= use_len;
		src += use_len;

		UPDATE_CBC_MAC;

		while (len_left > 0) {
			use_len = len_left > 16 ? 16 : len_left;

			memset(b, 0, 16);
			memcpy(b, src, use_len);
			UPDATE_CBC_MAC;

			len_left -= use_len;
			src += use_len;
		}
	}

	/*
	 * Prepare counter block for encryption:
	 * 0        .. 0        flags
	 * 1        .. iv_len   nonce (aka iv)
	 * iv_len+1 .. 15       counter (initially 1)
	 *
	 * With flags as (bits):
	 * 7 .. 3   0
	 * 2 .. 0   q - 1
	 */
	ctr[0] = q - 1;
	memcpy(ctr + 1, iv, iv_len);
	memset(ctr + 1 + iv_len, 0, q);
	ctr[15] = 1;

	/*
	 * Authenticate and {en,de}crypt the message.
	 *
	 * The only difference between encryption and decryption is
	 * the respective order of authentication and {en,de}cryption.
	 */
	len_left = length;
	src = input;
	dst = output;

	while (len_left > 0) {
		size_t use_len = len_left > 16 ? 16 : len_left;

		if (mode == CCM_ENCRYPT) {
			memset(b, 0, 16);
			memcpy(b, src, use_len);
			UPDATE_CBC_MAC;
		}

		CTR_CRYPT(dst, src, use_len);

		if (mode == CCM_DECRYPT) {
			memset(b, 0, 16);
			memcpy(b, dst, use_len);
			UPDATE_CBC_MAC;
		}

		dst += use_len;
		src += use_len;
		len_left -= use_len;

		/*
		 * Increment counter.
		 * No need to check for overflow thanks to the length check above.
		 */
		for (i = 0; i < q; i++)
			if (++ctr[15 - i] != 0) {
				break;
			}
	}

	/*
	 * Authentication: reset counter and crypt/mask internal tag
	 */
	for (i = 0; i < q; i++) {
		ctr[15 - i] = 0;
	}

	CTR_CRYPT(y, y, 16);
	memcpy(tag, y, tag_len);

	return (0);
}

/*
 * Authenticated encryption
 */
int mbedtls_ccm_encrypt_and_tag(mbedtls_ccm_context *ctx, size_t length, const unsigned char *iv, size_t iv_len, const unsigned char *add, size_t add_len, const unsigned char *input, unsigned char *output, unsigned char *tag, size_t tag_len)
{
	return (ccm_auth_crypt(ctx, CCM_ENCRYPT, length, iv, iv_len, add, add_len, input, output, tag, tag_len));
}

/*
 * Authenticated decryption
 */
int mbedtls_ccm_auth_decrypt(mbedtls_ccm_context *ctx, size_t length, const unsigned char *iv, size_t iv_len, const unsigned char *add, size_t add_len, const unsigned char *input, unsigned char *output, const unsigned char *tag, size_t tag_len)
{
	int ret;
	unsigned char check_tag[16];
	unsigned char i;
	int diff;

	if ((ret = ccm_auth_crypt(ctx, CCM_DECRYPT, length, iv, iv_len, add, add_len, input, output, check_tag, tag_len)) != 0) {
		return (ret);
	}

	/* Check tag in "constant-time" */
	for (diff = 0, i = 0; i < tag_len; i++) {
		diff |= tag[i] ^ check_tag[i];
	}

	if (diff != 0) {
		mbedtls_zeroize(output, length);
		return (MBEDTLS_ERR_CCM_AUTH_FAILED);
	}

	return (0);
}

#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
/*
 * Examples 1 to 3 from SP800-38C Appendix C
 */

#define NB_TESTS 3

/*
 * The data is the same for all tests, only the used length changes
 */
static const unsigned char key[] = {
	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
};

static const unsigned char iv[] = {
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
	0x18, 0x19, 0x1a, 0x1b
};

static const unsigned char ad[] = {
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
	0x10, 0x11, 0x12, 0x13
};

static const unsigned char msg[] = {
	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
};

static const size_t iv_len[NB_TESTS] = { 7, 8, 12 };
static const size_t add_len[NB_TESTS] = { 8, 16, 20 };
static const size_t msg_len[NB_TESTS] = { 4, 16, 24 };
static const size_t tag_len[NB_TESTS] = { 4, 6, 8 };

static const unsigned char res[NB_TESTS][32] = {
	{0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d},
	{
		0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62,
		0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d,
		0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd
	},
	{
		0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a,
		0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b,
		0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5,
		0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51
	}
};

int mbedtls_ccm_self_test(int verbose)
{
	mbedtls_ccm_context ctx;
	unsigned char out[32];
	size_t i;
	int ret;

	mbedtls_ccm_init(&ctx);

	if (mbedtls_ccm_setkey(&ctx, MBEDTLS_CIPHER_ID_AES, key, 8 * sizeof key) != 0) {
		if (verbose != 0) {
			mbedtls_printf("  CCM: setup failed");
		}

		return (1);
	}

	for (i = 0; i < NB_TESTS; i++) {
		if (verbose != 0) {
			mbedtls_printf("  CCM-AES #%u: ", (unsigned int)i + 1);
		}

		ret = mbedtls_ccm_encrypt_and_tag(&ctx, msg_len[i], iv, iv_len[i], ad, add_len[i], msg, out, out + msg_len[i], tag_len[i]);

		if (ret != 0 || memcmp(out, res[i], msg_len[i] + tag_len[i]) != 0) {
			if (verbose != 0) {
				mbedtls_printf("failed\n");
			}

			return (1);
		}

		ret = mbedtls_ccm_auth_decrypt(&ctx, msg_len[i], iv, iv_len[i], ad, add_len[i], res[i], out, res[i] + msg_len[i], tag_len[i]);

		if (ret != 0 || memcmp(out, msg, msg_len[i]) != 0) {
			if (verbose != 0) {
				mbedtls_printf("failed\n");
			}

			return (1);
		}

		if (verbose != 0) {
			mbedtls_printf("passed\n");
		}
	}

	mbedtls_ccm_free(&ctx);

	if (verbose != 0) {
		mbedtls_printf("\n");
	}

	return (0);
}

#endif							/* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */

#endif							/* MBEDTLS_CCM_C */
